Automatic extension-ladder lock.



no. 691,051. Patented ran, '14, I902.

FERGUSON. I AUTOMATIC EXTENSION LADDER LOCK.

' (Application filed Mar. 25. 1901.:

m, J" I all/ i y lw l l .1

Units States LYMAN-FERGUSON, OF ITHAGA, NEW YORK.

AUTOMATIC sxrsuslon moosa LOCK.

SPECIFICATION formingpart of Letters Patent No. 691,051, dated January 14, 1902.

Application filed March 25, 1901. Serial No. 52,848. (No model.)

"To aZZ whom it may concern.-

invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The invention relates to automatic extension-ladder looks.

The object of the invention is to improve the construction of the device shown in patent No. $0,885, dated June 24, 1900, and issued to C. N. Richardson, by providing a lock which shall be simple of construction, durable in use, and comparatively inexpensive of production.

In the above-mentioned patent the casing which incloses the hook and latch is cast with studs to receive holes formed in the ends of the latch and hook and act as pivots upon which said latch and hook turn. This construction has been found to be objectionable, for the reason that the hook and latch are materially weakened at the pivotal points of connection with the casing, and the studs being supported only at one end tend to snap or break off when weight is applied to the hook or latch, thus making an otherwise perfectly-operating device most uncertain and unreliable in operation.

A further object of the invention is to relieve the bolts used in connecting the lock to the ladder-section from undue strain incident to sudden shocks to which the laddersection is subjected.

With these and other objects in view the invention consists of certain novel features of construction, combination, and arrangement of parts, which will be hereinafter more fully described, and particularly pointed out in the appended claim.

In the accompanying drawings, Figure 1 is a side elevation of my improved automatic extension-ladder lock. Fig. 2 is a similar view with the face-plate of the casing removed, showing in full lines and in dotted lines the difierent positions assumed by the hook and latch. Fig. 3 is avertical sectional View through a fragment of the side piece of the ladder-section, illustrating the manner of connecting the casing to said side piece. Fig. i is a detail perspective view of the hook. Fig. 5 is a similar view ,of the latch.

In the drawings, 1 denotes the casing,which consists of the body portion 2, having'amarginal :side flange 3 and end flanges at, terminating in solid lugs 5, which have outwardlyprojecting studs 6, through which and the lugs are formed apertures 7.

8 denotes the face-plate having apertured lugs 9, through which and the lugs and the studs extend bolts 10 for securing the casing in position to one of the side pieces of the ladder, nuts 11 being screwed upon the outer ends of said bolts. To remove the strain from the bolts and prevent the accidental disengagement of the casing from the ladder, due to sudden shocks of unusual weight being placed upon the ladder, I sink or extend the studs 6 into sockets 12 in the inner face of the side piece or the ladder-section, as shown in Fig. 3, so that all vertical strain is resisted by said studs and removed from the bolts.

13 denotes the hook, and 14c the latch.

Instead of forming one side of the casing with a stud and the end of the hook with a hole to receive the stud, which construction is objectionable for reasons hereinbefore pointed out, I provide the end of the hook with studs 15, cast integral therewith and projecting into holes 16, formed in the sides of the casing, which construction has been demonstrated to be much stronger, practicable, and less liable to breakage, first, because the hook is not weakened to receive a pivotb0lt, and, secondly, the studs are cast integral with and project from the opposite sides of the hook, thus supporting the hook at opposite points and not at one end of the stud, as shown in the patent referred to.

17 denotes studs projecting from the opposite sides of the latch 14 and pivoted in holes 18, formed in the sides of the casing, and possess the same advantages over the construction shown in the patent above referred to as those set forth in the description of the hook 15.

19 and 20 denote, respectively, springs used for forcingthe upper end of the hook out wardly, and 21 denotes a spring for assisting in forcing the latch 14: outwardly.

As the operation of hooks of this character is well known in the art and as this hook Works in exactly the same manner as the hook shown and described in the patent above referred to, a description of the operation in the present instance is thought to be wholly unnecessary, and therefore will not be given.

The points of advantage possessed by a hook of this construction over the hooks heretofore in general use have been made clear and form the very gist of the present invention.

Having thus described my invention, what I claim, and desire to secure by Letters Patout, is- V .In a device of the character described, the combination with the side rail of a ladder having sockets formed therein, of an automatic locking device consisting of a casing having two side pieces formed with two sets of alined apertures and having one side piece formed with apertured studs to seat in said sockets, bolts extending through the side pieces of the casing, its studs and through the side piece of the ladder, a spring-actuated hook having integral oppositely-projecting lugs to engage one set of apertures of the side pieces of the casing, anda latch having integral oppositelyprojecting lugs to engage the other set of apertures of the side pieces of the casing, substantially asset forth.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

'LYMAN FERGUSON.

Witnesses:

JAs. O. G. KOEHL, BENJ. G. Gown. 

